Cis-platinum-(II)-diammine dichloride which is known under the USAN designation (United States Adopted Name) as cisplatin is used to a great extent as an anti-tumor acting material. However, the cisplatin obtained according to known methods of manufacture is always highly impure and it is suitable for medicinal use only after cumbersome and wasteful purification.
Until now the best known methods of purification consist of a recrystallization of cisplatin from dimethylacetamide in the presence of 0.1N HCl (J. D. Hoeschele, T. A. Butler, J. A. Roberts, C. E. Guyer, Radiochim. Acta, Volume 31, page 27 (1982). This recrystallization, however, results in considerable losses of cisplatin (15-20%). Besides, the cisplatin obtained according to this procedure does not fulfill the purity requirements placed on a medicine.
European patent application No. 30782 discloses purifying cisplatin by recrystallizing from dimethylformamide in the presence of 0.1N HCl at room temperature, e.g. Step 7, page 9. However, there is not obtained an adduct of cisplatin with the dimethylformamide as is obtained in the process of the invention. Besides the yield of cisplatin after the 3rd recrystallization is lower than in the process of the present invention described below.